On the fourth night of the Republican National Convention, crime got a great deal of attention. Former New York Mayor Rudy Giuliani accused the current Democratic leadership of that city of turning it into a bloody dystopian hellscape. "Don't let Democrats do to America what they've done to New York," he said, warning against the "progressive Democrat approach to crime, which is to do nothing substantive to reduce it." Patrick Lynch, head of the New York Police Benevolent Association, endorsed Trump because of a looming "public safety disaster."
This is hysterical fearmongering. First, as Jon Hilsenrath writes at the Wall Street Journal, in 2020 murders are up quite a lot in some cities like Austin and Chicago, but only moderately in Los Angeles and Charlotte, and were actually down in San Jose. Overall crimes are down compared to last year, and even murder victims are still far below where they were 20-30 years ago. Indeed, this year the rate of homicides in New York is considerably less than it was in the last year of Giuliani's mayoralty.
Second, as Michael Hobbes writes at the HuffPost, data suggests that murders are up in part because people are now reluctant to call the police, thanks to how wider coverage of police brutality has harmed the reputation of law enforcement. People are less likely to help solve murders if they are rightly terrified that any contact with police might lead to a beating or getting shot.
Moreover, the main factor that has changed over the last few years is the election of Donald Trump. It is true that Democrats are in charge of local government in many big cities, but they were also in charge from 2009-2016, when crime declined steadily across the country. Once more Trump's campaign argument amounts to "elect me to stop the reign of terror I am currently presiding over."